Desiccating method and apparatus



Patented June 20, 1933 1 UNITED STATES PATENT OFFICE DAVID D. PEEB1 ES,OF EUREKA, CALIFORNIA Application filed July 16, 1928. Serial No. 293,198.

This invention relates generally to methods and apparatus for treating a fluid suspension of solids in a gaseous medium. More particularly it relates to methods and apparatus fordesiccating divided solids, especially organic material such as milk products. The invention, however is not to be understood as restricted to the treatment of organic materials.

It is an object of this invention to devise a novel method and apparatusfor sustaining swirling air currents within a. chamber used in the treatment of divided material.

It is a further object of this invention to generally improve upon apparatus of the general character described in my copending application No. 164,991 filed January 31, 1927, since matured into U. S. Letters Patent No.

I 1,830,174 whereby its operation is made more economical'and effective.

It is a further object of this invention to devise a novel method and apparatus particularly adapted for the drying or desiccating of organic substances such as milk prod- F nets and which makes possible the use of relatively high drying temperatures.

Further objects of my invention will appear from the following description in which I have set forth the preferred embodiment of my invention. It is to be understood that the appended claims are to be accorded a range of equivalents consistent with the state of the prior art.

Referring to the drawings:

Figure 1 is a side elevational view in cross section illustrating apparatus incorporating my invention.

Fig. 2 is a plan view of the apparatus shown in Fig. 1.

Fig. 3 is a side elevational view in cross section illustrating the treatment chamber which I employ and its associated parts.

Fig. 4 is a cross sectional view taken along the line H of Fig. 8.

In my aforementioned application No. 164,- 991 filed Jan. 31, 1927. I have disclosed a novel method and apparatus for effecting treatment'of divided solids in a gaseous medium, one of the principal features of which is the use of a plurality of nested zones within suspension by the gas, are removed from the system from one of the outer zones. By utihzmg a plurality of zones of this character within a s'ngle treatment vessel, the solids have a comparatively long period of suspension before being removed from the chamber and are effectively contacted by the currents of gas because of deceleration and accelcra tion of the particles when moving from one zone to another. I have found that with such a method it is possible to maintain two or more temperature zones within the chamber, corresponding to the different zones of swirling gas currents. As will be presently described, I have also deviseda novel method and apparatus for maintaining the outer zone of swirling gas within a treatment chamber. References herein to the introduction of divided solids into the treatment chamber are I intended to include cases in which solids are able source such as a fan or blower 11 which is connected to chamber 10 thru conduits 12 and 13. T oprovidc a convenient means for forming an inner zone of swirling gas currents within the treatment chamber 10, I prefer to introduce the gas from conduit 13 tangentially into a sub-chamber 14 which communicates with the upper portion of treatment chamber 10 thru an opening 16. To provide means for forming an outer zone of swirling gas currents, I preferably provide a suitable gas moving device such as a blower 17 having its intake conduit 18 connecting with chamber 10 and its discharge conduit 19 connected tangentially with the peripheral portion of chamber 10. The tangential direction in which conduit 19 is directed is opposite to that in which conduit 13 is directed. The intake conduit 18 can be connected with the treatment chamber 10 at a number of dif- 109 tcrcnt points. although ,l pretcr to make this connection near the outer peripheryof chamher It). and likewise l prefer to malve it tangentially so as to aid in inducing swirling currents of air.

The i'naterial to be treated. as for example a liquid milk product. is introduced into chamber 10 thru pipe 21. this pipe 'rct'erahly dischar ljiug thru a suitab'c spray nozz e 22 which is arranged at or near the vertical axis of the chamber it), In addition to the discharge thru conduit 13 I prefer to al o introduce gas into the inner portion of suh-chamher l-l. tor a purpose which wi l he presently made clrar. 'lo cilia-tthis result. 1 have shown a conduit 23 connectial with the discharge conduit 12 ol blower t l and to the upper portion oi the suh--chan|ln-r ll. \Vithin the sulrchamhcr ll. there i p1 oridcd a pcrto rated member communicat ing w th conduit 2 and haring its .lower end provided with an opening it surrounding and adjacen to the nozzle 22.

lnstead of ellect'ing separation l' tween gas and solids within the treatment chamber 1t), -l prefer to continuously remove gas from the treatment chamber together with suspended solids. For example 1 have shovn a discharge conduit- 2T connected tangentially with the peripheral portion ot treatn'ienl chamber 10. Conduit 27 preferably conveys the fluid Hspi'IiSion of solids 2 nd ga o suitable separating means :28. from which the separated solids can be removed from the lower opening '29 and from which the scpa ate gas is di charged thru conduit ill. As my apparatus and meth d i de-igncd particularly l'or etl'ecting drying ol' material. 1 preferably heat th air iufrwluccd thru conduits l3 and :33). For this purpose I have shown the air discharged from hlower 11 passing thru a suitable h nlet" 12. ihis hcater having pipe conncctions 32-3 and ll for inllow and discharge of heating fluid. 7

In order to prevent solids from sticking to the inner walls of the treatment chamber it prefer to employ a rotary brush or ralio comprising a frame 36 pivotally mounted at -37 to rotate within the chain Chains 38 are secured to this frame and serve to scrape the inner walls. vanes ell'cct rotation by reaction with the swirling gas.

The operation oi my method can best be understood by reference to Figs. 3 and t. lly continuously introducing air or other suitable gas thru conduit: 12% with considerable velocity, a zone A is formed which consists of swirling currents of air. The motion of this air is cyclonic, or may he termed vortical. binmltaneou operation of blower 1T removes gas and suspended solids from the chamber and reintrodnces the same tangentially thru the conduit 19. The kinetic energy of gases discharged from conduit 19 rauses another zone B of swirling currents of gas about the zone A. Beaiuse of the direction in which gases are discharged "from conduit it), the currents of gas in the outer zone B move about and in an opposite direction to movement of gas currents in zone A. The movements of the gas currents in zones A and B is sutlieiently 'apid that these zones are maintained distinct and sepa ate. As gas is continuously introducial into the inner zone A, this gas progresses into zone i. a portion is removed and reintroduced thru conduit; 19, and a portion finds its way into the discharge conduit 27. The kinetic energy impart d to gas forming the zone is dissipated along the outer pcripheuv of this zene and the n'iovement of gas is deceleratml and then accele 'ated in the opposite direction when itv caught up hy the air currents in zone B. \l'hen solid particles are introduced into the inner zone as for example milk sprayed thru the nozzle 22, these solid particles are caught up and caused to swirl about together with the air currents. Due to centrit'ugal force, the solid particles tend to pro ress toward the outer portion of zone A, where they are decclerated in attempting to progress from zone A to zone 1. 'hen the particles ljiegin to enter zone I). they are alight up by this zone and accelerated to again swirl in a direction opposite to the swirling movement in zone A. Finally the particles find their way into the discharge conduit 27. Y

\Vhen drying solids, it is apparent that the particles are under favorable drying conditions while within the chamber 10. The movement of each particle involves both acccle 'ation and deceleration in the passage. thereof outu'ardlr thru the inner swirling zone and into the outer swirling zone, and .--ince the particles themselves are caused to swirl about. the ext nt or time of contact be tween the gases and the particles will lie of such a nature a to give optimum drying etl'ect.

The introduction of gas thru conduit. 23 is not essential but is to be preferred for hest; results. The etlcct of introducing gas at this point is to increase the pressure within the inner portion of suh-chamlwr ti. and thus increase the gas pressure of the inner portion of zone A. The net result accomplished is to prevent the solid particles introduced from being d awn up into the sub-chamher l4.

' In using my method and apparatus. it is possible to introduce the gas thru conduits and 2?, at a relatively high temperature, without iujuriously e'llecting organic substances, as for example milk products, For example when n.-;ing the appa 'atus as a milk dryer, 1 utilize a temperature of air introduced thru conduit: 13 and 3 in the neighborhood of 400 degrees F. lVhcn operating under these conditions the temperature of 'out' injury.

' humidity i into the chamber, causing 45 the saturated air bein discharged from conduit 27is in the neigh JOlliUOd of 220 degrees F. When the milk is introduced into zone A, it is first subjected to dry air at the maximum temperature, but since the particles at this time have a maximum amount of moisture, evaporation of this moisture keeps the temperature of the particles at a much lower temperature at which the particles are not injured. As the percentage of moisture entrainedhy the particles decreases, they cannot withstand such a high temperature with- Howeverwhen this takes place, are in the outer zone Brand the temperature of the surrounding gas is correspondinglylower. Thus in my method it is to be noted that the particles when in wet condition are first. subjected to a high temperature air or drying medium, and as the moisture content of the particles decreases, the temperature of the surrounding air is correspondingly decreased and the of the surrounding air is correspondingly increased. At the point of discharge, the temperature of the air is lowest, the humidity is greatest, and the moisture content of the particles is least.

I claim:

1. In a method of treating divided solids carried by a gas characterized by the use of a treatment chamber, the steps of continuously introducing gas and said solids into said chamber, continuously removing gas and solids from said chamber, separating solids from a portion of the gas so removed, and continuously reintroducing another portion of the removed gas and solids into the chamber adjacent the periphery thereof in a tangential direction.

3. in a method of treating divided solids carried by a gas characterized by the use of a treatment chambcr, the steps of continuously the particles sid gas to swirl aboutat arapid rate within the chamber, r'emotfing gas and suspended solids from the chamber and reintroducing the same into the chamberin a tang'rential direction to effect a swirling of gas around sald first swirlmg movement and m an opposlte direction, and

removing treated solids from" the system;

A dry' ing apparatus comprising a chamfor introducing heated gas and swirl about in an inner zone 'ofsaid chamher, and means for causing gasand suspendedsolids to swirl about'ina zone surrounding said inner zone and in an opposite direction, said means comprising means for remov ng gas from thechamber and for intrcduci'ng the same mtoih 'chamb-erin a "tangentialdirectionlf drying apparatus comprising a chainte'r; mass ar==iata aucing haea ates- 1 introducing gas and suspended solids time suspended solids into said chamber, means for causing introduced gas and solids to swirl about in an inner zone means for causing gas and suspended solids to swirl about in a zone surrounding said inner zone and in an opposite direction, said means comprising means for removing gas from the chamber and reintroducing the same into the chamber in a tangential direction, and means for continuously removing suspended treated solids from the system. i

5. A drying apparatus comprising a chamber, means for introducing heated gas and suspended solids into said chamber, means for causing introduced gas and solids to swirl about in an inner zone of said chamber, means for causing gas and suspended of said chamber,

solids to swirl about in a zone surrounding said inner zone and in an opposite direction, said means comprising means for removing gas from the chamber and reintroducing the same into the chamber in a tangential direction, means f or separating gas from suspended treated solids, and means for conveying gas and treated suspended solids from said chamber to said separating means. 6. A drying apparatus comprising a chamber, means for introducing heated gas and suspended solids into said chamber in a tangential lirection thereby causing the gas .to swirl about in an inner zone-of said chamber, means for causing gas and suspended solids to said inner zone and in an opposite direction, said means comprising means for removing gas from the chamber and reintroducing the same into the chamber in a tangential direction, means for separating gas from treated solids, and means for conveyim gas and treated suspended solids from said chamber to said separating means. i j

7; A drying apparatus comprising a chamber, means for introducing" a relatively high tern "erature drying gas" into saidchamber cated in. divided condition finto'said inner zone, and means "for forming a lyjQlow'er 't emperature outer zone about and communicating with said inner zone, said means including means for removing gasj aii d materiahfrom the outer'zone and for reintroducing the same into said outer zone. 4 f8} Adi'ying appara ber, means for introducing a column of temperature drying v adjacent the axis of thesame, ing an inner high temperature zone, means for forming a relatively low' temperature zone of swirling ,gas about and communicating with the inner zone, said' means includhigh re rfe mtags, conduit for removing gasand particles from the outer zone, a'cor duitifor reintro- (lacing-remove as theoiiter zone,-' la "an beating a? new urgesthru=said ftb orm an innerfhigh temperature zone,

substantiah,

swirl about in a zone surrounding tus comprising a cham gas into the chamber 110, cans for introducing material to be 'desi c.'

couduits, means for introducing divided material to be dried into the inner zone, and means externally of said chamber for continually separating dried particles from the "El/S. a 9. A drying apparatus comprising a chamber, means for introducing a relatively high temperature drying gas into said chamber to form an inner high tom )erature zone, means for introducing material to-be desiccated into the inner zone in divided condition, means for forming a substantially lower temperature zone of gas swirling about the inner zone, said means including a conduit for removing gas and suspended solids from the outer zone, a blower having its inflow side connected to said conduit, and a conduit connecting the outflow side of the blower to said outer zone, said blower and conduits serving to reintroduce gas into the outer zone without effecting separation of suspended solids, means for continually diverting gas and suspended solids from the chamber, and means externally of said chamber for efi'ecting a separation of dried-particles from said last mentioned gas.

10. In a method of desiccatin material characterized by the use of a desiccating chamber, the steps of continuously introducing desiccating gas and divided particles of the material into the chamber to efli'ect 'a suspension of the particles in the gas, maintaining a high temperature zone and relatively a low temperature zone in said chamber, the gas and particles being initially introduced to said high temperature zone, continuously passing gas and particles from the high temperature zone into the low temperature zone, continuously removing gas and suspended particles from the low temperature zone, reintroducing a portion of the removed gas and suspended particles into the low temperature zone without effecting a se )aration between the particles and gas, and e ecting a separation of the particles from the remaining portion of the removed gas externally of said chamber.

11. The methodas defined in claim 10 further characterized in that said low temperature zone surrounds said high temperature zone.

12. The method as defined in claim 10 further characterized in that said low temperature zone surrounds said high temperature zone and in that the gas and particles in the two zones are swirled in opposite directions.

13. In a method of desiccating material characterized by the use of a desiccating chamber, the steps of continuously introducing desiceating gas and divided particles of the material into the chamber to-efi'ecta suspension of the particles in the gas, maintaining a high temperature, zone andrelatively a low temperature zone insaid chamher, the gas and particles being initially inwere.

the low temperature zone in the opposite direction, continuously removing gas and suspended particles from thelow temperature zone, reintroducing a portion of the removed gas and suspended particles into the low temerature zone without effecting a separation between the particles and gas, and cileeting a separation of the particles from the remaining portion of the removed gas externally of said chamber.

14. In a method of treating divided solids carried by a gas characterized by the use of a treatment chamber, the steps of continuous- 1y introducing gas and said solids into said c amber adjacent the center thereof, continuously removing gas and solids from the eriphery of said chamber, separating solids from a portion of the gas so removed and continuously reintroducing another portion of removed gas and solids into the chamber adj acent the periphery thereof in a tangential direction.

15. In a method of the character described, characterized by the use of a treatment chamber, the steps which comprise introducing gaseous med um at relatively high temperature adjacent the central portion of said chamber and causing such gaseous medium to swirl within an inner zone in said chamber, introducing non-gaseous material in divided form into the relatively high ten1perature gaseous medium in said inner zone and causing such material to move outwardly through said inner zone by centrifugal force, continually removing gaseous medium at relativel low temperature from said chamber outsi e said inner zone and reintroducing such gaseous medium into the outer portion of said chamber in a substantially tangential direction opposite to the direction of whirling movement in said inner zone, so as to maintain an outer swirling zone of gaseous medium of relatively low temperature swirling in the opposite direction to the gaseous medium in the inner zone, and in position to receive the divided material thrown out of said inner zone by centrifugal force, whereby said divided material is caused to also whirl in said outer zone and is prevented by centrifugal force from returning to said inner zone.

1.6. The method of treating a non-gaseous material by contact with a heated gaseous medium in a treatment chamber, which comprises introducing finely divided particles of non-gaseous material to be treated into suspension in a gaseous medium within a treatment chamber, continually withdrawing gaseous medium and. suspended particles of said material from said chamber and re-introducing said gaseous medium and particles into said chamber so as to maintain recirculation'thereof in a closed system including 5 said chamber, retaining substantially all the particles of material in suspension in said gaseous medium throughout the recirculation system, heating a supply of gaseous medium separate from the recirculated gaseous me- 1 dium and introducing said heated gaseous medium into the recirculation system, eontinuall removing gaseous medium and suspende( particles from the recirculation s 5- tom at a position removed from the posit1on of introduction of said heated gaseous medium, and separating suspended particles from the gaseous medium so removed.

17 The method as set forth in claim 16, in which the non-gaseous material to be treat- 29 ed and the supply of heated gaseous medium are both introduced into the treatment chamber adjacent the central portion thereof, while the recirculated gaseous medium and suspended particles are reintroduced into the treatment chamber adjacent the periphery thereof and in a substantially tangential direction so as to maintain active whirling movement of the recirculated gaseous medium and suspended particles within an out- 30 er zone in said-chamber.

18. The method as set'forth in claim 16, in which said heated gaseous medium is introduced into the recirculation system by in- 1 troducing the same into the treatment chamher adjacent the position of introduction of said non-gaseous material to be treated. 19. The method as set forth in claim 16, in which the heated gaseous medium is introduced into the recirculation system'by in- 40 troducing the same adjacent the position of introduction of the non-gaseous material to be treated and in such manner as to cause said heated gaseous medium to contact first the freshly introduced non-gaseous material so as to be cooled thereby before coming in contact with the suspended particles contained in the recirculated gaseous medium. Intestimony whereof, I have hereunto set my hand.

DAVID D. PEEBLES. 

